McConnell is facing a conservative challenger in businessman Matt Bevin, who was recently endorsed by the Senate Conservatives Fund, a national conservative group that has been airing ads hitting McConnell for the past year.

The attacks have fueled an ongoing feud between SCF and McConnell and his allies in what's become a proxy battle for a larger conflict within the Republican party between its conservative grassroots and the establishment wing of the party.

McConnell again knocked SCF — the only conservative group he was willing to discuss — in his WSJ interview. He accused the group of electing "more Democrats than the Democratic Senatorial Committee over the last three cycles."

"Right now they're on the air in obvious coordination with Harry Reid's super-PAC — Harry Reid's! — in the same markets, at roughly the same amount, at the same time," he said, a reference to ads launched against him by the Democratic Senate Majority PAC.

McConnell said while he agrees with the Tea Party, many of the movements followers are "being misled."

"I think it's irresponsible for some people to characterize themselves as sort of true conservatives, to mislead their followers into believing you can get an outcome that you can't possibly get," he said.

"I make a distinction between the leaders and the followers (of the groups). I mean, I think a lot of well-meaning people are sending money to organizations having no idea they're gonna spend all that money against Republicans. Because they're being misled."

McConnell said he takes issue with the leaders of some of the groups "who basically mislead them for profit. ... They raise money ... take their cut and spend it" in ways that hurt Republicans.

A number of establishment actors and groups have echoed McConnell's complaints after the conservative-led shutdown prompted national backlash against the GOP and a caused significant hit to the party's brand.

Business groups have pledged to become more involved in primaries to push back against the Tea Party, and other establishment figures have, like McConnell, questioned the motives of some of the nation's largest conservative organizations.

McConnell said that to win the Senate back, the GOP needs to "run candidates that don't scare the general public, [and] convey the impression that we could actually be responsible for governing, you can trust us — we're adults here, we're grown-ups."

Underlying his comments were the memory of winnable seats lost by weak, gaffe-prone GOP nominees over the past two cycles, like former Rep. Todd Akin (R) in Missouri, whose bid was derailed by controversial comments about pregnancy and rape.

McConnell denied the suggestion that the GOP is waging a civil war between those two factions, and insisted the party in its entirety agrees in its opposition to ObamaCare.

But he repeated his pledge that the shutdown won't happen again, and said that had the party avoided the situation, they'd be in a much stronger position politically.

"Learn from your mistakes, and realize that had we been talking ObamaCare during that 16 days, instead of people being consumed with the shutdown, we'd probably have a generic party ballot lead right now," he said.